Crab Nebula (M1; NGC 1952)

The nebulous remnant in the constellation Taurus
of a supernova that exploded in AD 1054. In coloured photographs it appears
as a network of red filaments surrounding an elliptical area of pale white
light. This white light is synchrotron radiation generated by hot ionized
gas in a magnetic field. The filaments are the outer layers of the star
that were blown off in the explosion and are travelling outwards at about
1,500 km/s.
The core of the star that exploded remains at the centre of the nebula.
It is now a pulsar. Electrons emitted by the pulsar are responsible for
the synchrotron radiation. The interval between flashes from the pulsar
is 33 milliseconds; flashes are seen in visible light as well as the radio
pulses.